In the polyamide preparation field there are numerous reported attempts to device rapid polymerization processes permitting rapid moulding of nylon products. Various such attempts are now disclosed.
According to the process disclosed in U.S. Pat. No. 3,304,291, lactams may be polymerized by means of an alkali or alkaline earth metal catalyst and another compound which activates the alkaline-catalyzed polymerication of lactam. According to that U.S. patent, the derivatives of urea, thiourea and guanidine are particularly suitable as activators. An example of such a compound is lactam-blocked 1,6-hexamethylene diisocyanate.
The European patent application No. 134616 described a process for polymerizing lactams in the presence of an alkaline metal catalyst and a polymer activator. The polymer activator may be obtained by reacting a highmolecular polyol with a lactam-blocked diisocyanate. According to that application, products are obtained that possess high impact strength.
U.S. Pat. No. 3,862,262 describes the preparation of nylon block copolymers in the presence of a metal compound and a condensation product of an acyl-bis-lactam, and a polyol.
British Patent No. 1,067,153 describes the application of the reaction product of polypropylene glycol, and 2,4toluene diisocyanate as accelerator for the anionically catalyzed polymerization of lactam.